I'm using n (Node version management)
You can install it in two ways
brew install n
or
npm install -g n
You can switch between different version of node and io. Here's an example from my current env when I call n without params:
$ n
io/3.3.1
node/0.12.7
node/4.0.0
node/5.0.0
? node/5.10.1